1. Field of the Invention
This invention relates to suspension means for a railroad car truck and more particularly to a device for dampening or depressing oscillations between a bolster of the truck and side frames of the truck.
2. Prior Art
Trucks used with modern railroad cars are well known and generally include two spaced side frames which resiliently support therebetween ends of a truck bolster positioned transversely to the side frames. The resilient support of the bolster is provided, as an example, by a plurality of coil springs positioned within a opening formed in each side frame on which each end of the bolster is carried.
To dampen oscillations inherent in a coil spring type suspension, common dampening devices include a pair of friction shoes positioned on each side of a longitudinal axis of the truck bolster with each having an inclined wear surface for engaging with a like inclined friction surface formed in the bolster and a vertical wear surface for engaging with a vertical wear plate fastened to sidewalls of the side frame opening. Such an arrangement provides a three directional restraint to movements between the side frame and the bolster with substantial dampening of vertical movements and slight dampening of lateral movements.